As I said, I will leave the energy draining to be balanced by the team. But, even if you mastered the form, it will still dragin energy, but incredibly LESS/LITTLE.
As for the turbo+e recharge, its a great idea. For example, in normal form, you press e+turbo, your recharging rate is still the same, no change. But for the saiyans in any of the SSJ or higher forms, when you recharge by pressing e and with the turbo on, it will recharge slightly faster. That is abit to the realism in the DBZ series too. This should only apply to the Saiyan Race characters. Since Frieza and other non saiyan doesn't have the energy drain in their form, this e+turbo will slightly improve the advantages to balance out the transformations on saiyan and non saiyan.
******************note*******************
*Saiyan Race characters* = Normal form recharges as normal. SSJ and higher form recharges slightly faster with turbo on. Transformations drains energy.
*non Saiyan characters* = All forms recharges as normal. Trans doesn't have energy draining.
Btw ravendust, I think you get the wrong idea about robby's post. he said, until you master it, you will get no penalty. He must have typed it wrong. Or just needs to practice his english

But I know what he means.